Vitamin B12 deficiency is a common problem that affects the general US population and the elderly in particular. The elderly are at risk for preclinical vitamin B12 deficiency due to the increased presence of B12 malabsorption and atrophic gastritis as a consequence of aging. The deficiency of vitamin B12 in the elderly has potentially serious complications including dementia, Alzheimer's disease, and cancer. Current approaches to diagnosing B12 deficiency are inadequate because they lack specificity, have poorly defined reference ranges or are expensive. Our proposed test, known as the B12 Breath Test (BBT), will have the advantage of being non-invasive, be easy to administer and have a long shelf life. The BBT will allow physicians to accurately test for B12 deficiency at a much lower cost than current diagnostic tests. Our goal is to identify vitamin B12 deficiency in a preclinical stage when treatment can avert complications. Diagnosing this deficiency is meaningful because once identified as a problem, it can be effectively and inexpensively treated with appropriate vitamin B12 supplementation. This will lead to lower overall medical costs as this condition is quickly identified and appropriately treated. The underlying scientific principle of the test is that the metabolism of propionate is limited by the availability of vitamin B12. Thus, after orally administering a tracer dose of 13 C (non-radioactive) labeled propionate, the amount of 13 CO2 is reduced in the breath of vitamin B12 deficient individuals compared to those individuals with normal B12 status. The phase I grant demonstrated the feasibility of this concept. In Phase II we will refine the testing procedure with the goal to reduce test costs and simplify the test. Specifically, we will examine a smaller dose of propionate, a single 20-minute breath collection and eliminate the need to be in a fasted state for greater than 1 hour. The final product developed after Phase III will be an FDA approved diagnostic kit. This kit will be sold to our current clinical laboratory customers, to other independent clinical labs and to the more than 1,000 physician laboratories that have point-of-care breath testing equipment. [unreadable] [unreadable] Project Narrative: Vitamin B12 deficiency is a common problem found in the elderly that is difficult to identify early because there isn't an accurate and low cost diagnostic test. The deficiency of vitamin B12 has potentially serious complications including dementia, Alzheimer's disease, and cancer. The proposed test will address this diagnostic need and lead to better quality of life for these patients because vitamin B12 deficiency can be easily and inexpensively treated with vitamin supplements. [unreadable] [unreadable] [unreadable]